West African leaders have pledged one billion U.S. dollars to combat the spiraling threat of Islamist militancy in the region, the head of the regional ECOWAS bloc said on Saturday.

Groups with links to al-Qaeda and ISIL have strengthened their foothold across the arid Sahel region this year, making large swathes of territory ungovernable and stoking local ethnic violence, especially in Mali and Burkina Faso.

The 15 members of the West African bloc and the presidents of Mauritania and Chad had gathered for an extraordinary summit in Burkina Faso's capital, Ougadougou, to address the growing insecurity.

ECOWAS Commission President Jean-Claude Kassi Brou said the commission had decided to "contribute financially and urgently to joint efforts in the fight against terrorism" by pledging one billion U.S. dollars.

Brou also called on the United Nations to strengthen its MINUSMA peacekeeping mission, which has been based in Mali since 2013.

In July, the UN said Islamist attacks were spreading so fast in West Africa that the region should consider bolstering its response beyond current military efforts.

In 2017, five countries – Burkina Faso, Niger, Chad, Mali and Mauritania – backed by France, launched the G5 Sahel taskforce to combat the insurgents. But the initiative has been perennially lacking of fund.

The situation in Burkina Faso has deteriorated in particular in recent weeks. An attack in late August killed 24 soldiers, one of the heaviest losses yet in the nation's fight against Islamist militants. Last week, 29 people were killed in separate attacks in its troubled central-northern region.

Once a pocket of relative calm in the Sahel, Burkina has suffered a homegrown insurgency for the past three years, which has been amplified by a spillover of jihadist violence and criminality from its chaotic neighbor Mali.